Measuring Chase Utley’s Impact

Hey, have you heard the news? Chase Utley is back. He will be making his 2011 debut today against the Cincinnati Reds, the culmination of a long and arduous battle back from patellar tendinitis. At one point earlier during his rehab, Utley needed to sit on a stool to field ground balls; today, he will be doing so freely in a Major League game.

With the offense struggling — it hasn’t scored more than three runs in a game since Friday, May 13 — getting Utley back is huge. As a team, the Phillies compiled a .306 wOBA, a shade below the .312 league average. The return of Utley, assuming good health, will be a boon to the offense. Pete Orr, who had a .258 wOBA, was optioned and Chase’s consistent playing time should significantly cut into the AB’s for Wilson Valdez (.254 wOBA) and Michael Martinez (.202 wOBA). Overall, the offense was nearly nine runs below average, which equates to one win.

We convert wOBA to runs with the following equation:

( ( Player’s wOBA – League average wOBA ) / 1.15 ) * Player’s PA

Using PECOTA’s 50th percentile projection, Utley is expected to post a .383 wOBA in 400 PA for the rest of the season, which amounts to nearly 25 runs, or two and a half wins. That is, uh, quite an improvement over Orr and Valdez, who combined to be nearly nine runs below average in 117 PA (-31 runs in 400 PA). In other words, getting Utley back and severely reducing the roles of his replacements should net the Phillies roughly five and a half wins theoretically. The 50th percentile projection assumes a career-worst season for Utley as well, so Utley could be worth more offensively if he’s back to his usual self.

Then there’s Utley’s defense. It’s no secret that Utley grades out as one of the best defensive second basemen in baseball (arguably the best pre-injury). In over 8,200 innings, Utley has saved 80 runs more than an average second baseman according to UZR (an average of one run above average per 102 innings). If Utley does not decline defensively, he should save about ten runs defensively. In 383 combined innings, the combination of Orr and Valdez have saved 1.4 runs less than an average second baseman would.

We have passed the one-quarter mark of the season. Still, the return of Utley could net the Phillies upwards of six and a half wins. Last year’s contest with the Atlanta Braves was decided by six games, and it figures to be much closer by the time October 2011 rolls around. Getting a healthy, productive Utley back could be the difference between playing October baseball and playing October golf.